A135060 - OEIS

%I #14 Mar 17 2022 01:05:02

%S 1,2,6,12,60,120,840,840,2520,2520,27720,55440,720720,720720,1081080,

%T 2162160,36756720,36756720,698377680,698377680,698377680,698377680,

%U 16062686640,48188059920,160626866400,160626866400,160626866400

%N a(n) is the smallest number m for which none of the first n multiples of m has twice as many divisors as m.

%C a(n) is smallest integer m such that A129902(m)/m > n.

%C Conjecture: every number in this sequence is also in A002182. [_J. Lowell_ disproved this conjecture at a(24) = 48188059920. - _Ray Chandler_]

%C The conjecture that every term is a multiple of the preceding term is disproved at n = 15; a(15) = 1081080, which is not a multiple of a(14) = 720720. - _J. Lowell_, Jun 06 2008

%H Ray Chandler, <a href="/A135060/b135060.txt">Table of n, a(n) for n = 1..130</a>.

%e 60 is not a(6) because 60 has 12 divisors and 60*6=360 has 12*2=24 divisors.

%K nonn

%O 1,2

%A _J. Lowell_, Feb 11 2008, Jul 08 2008, Jul 14 2008

%E More terms from _J. Lowell_, May 13 2009

%E Inequality in the comment corrected and a(16) added by _R. J. Mathar_, Nov 04 2009

%E Extended by _Ray Chandler_, Nov 10 2009